US4136313A - Apparatus for measuring q-quality of oscillatory circuit components - Google Patents

Apparatus for measuring q-quality of oscillatory circuit components Download PDF

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Publication number
US4136313A
US4136313A US05/837,849 US83784977A US4136313A US 4136313 A US4136313 A US 4136313A US 83784977 A US83784977 A US 83784977A US 4136313 A US4136313 A US 4136313A
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frequency
unit
input
output
measuring
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Viktor V. Molochnikov
Vasily I. Efimov
Anatoly S. Veraxo
Evgeny M. Savitsky
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    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
    • G01R27/00—Arrangements for measuring resistance, reactance, impedance, or electric characteristics derived therefrom
    • G01R27/02—Measuring real or complex resistance, reactance, impedance, or other two-pole characteristics derived therefrom, e.g. time constant
    • G01R27/26—Measuring inductance or capacitance; Measuring quality factor, e.g. by using the resonance method; Measuring loss factor; Measuring dielectric constants ; Measuring impedance or related variables
    • G01R27/2688—Measuring quality factor or dielectric loss, e.g. loss angle, or power factor

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  • the present invention relates to instruments for measuring parameters of radio circuits, and more particularly to an apparatus for measuring the Q-quality of oscillatory circuit components.
  • the apparatus according to the present invention is mainly used for measuring "Q" of inductors and tangent of loss angle in capacitors, as well as for measuring the active resistance, capacitance, inductance and tangent of loss angle in dielectric materials.
  • the apparatus can likewise be used for measuring parameters of linear and nonlinear radio components.
  • the apparatus also includes a step voltage generator connected to the units for producing the first and second frequency derivatives of the amplitude-frequency response of the oscillatory circuit and electrically coupled to the frequency modulator. Furthermore, the apparatus includes an amplifier, the drive input of which is connected to the step voltage generator and the output, to the drive input of the frequency modulator, while another input thereof is electrically coupled to the unit for producing the second frequency derivative of the amplitude-frequency response of the oscillatory circuit.
  • an attenuator connected to the unit for producing the second frequency derivative of the amplitude-frequency response of the oscillatory circuit and electrically coupled to the amplifier input
  • a subtracting unit connected, in turn, to the amplifier, attenuator and to the units for producing the first and second frequency derivatives of the amplitude-frequency response of the oscillatory circuit, the output of the subtracting unit being electrically coupled to a Q-readout unit.
  • the apparatus fails to provide for high accuracy of measuring the Q-quality in a wide frequency range because of the frequency dependence of transfer ratios of the measuring unit coupling elements and due to errors associated with maintaining the measuring unit input voltage constant, since the second frequency derivative of the amplitude-frequency response, of the oscillatory circuit in said apparatus is used as an absolute analog value for measuring the Q-quality and depends on the transfer ratios of coupling elements and on the absolute value of the input voltage of the measuring unit.
  • an apparatus for measuring the Q-quality of oscillatory circuit components comprising a control unit whose sawtooth generator is electrically coupled to a high-frequency generator connected to a frequency modulator, the output thereof being connected to a measuring unit electrically coupled, in turn, to the oscillatory circuit components whose Q-quality is to be measured, and a unit for producing the first frequency derivative of the amplitude-frequency response of the oscillatory circuit, this unit being connected to a control unit null device connected in series with the control unit sawtooth generator, to a unit for producing the second frequency derivative of the amplitude-frequency response of the oscillatory circuit, and to a peak detector connected, in turn, to the measuring unit.
  • a low-frequency generator electrically coupled via an electronic switch to the frequency modulator, a second control unit having a null device connected in series with a sawtooth generator, a memory unit connected to the sawtooth generator of the second control unit and to the low-frequency generator, a unit for measuring the frequency ratio, connected to the low-frequency and high-frequency generators, a second memory unit electrically coupling the high-frequency generator to the control unit, and a third control unit connected to the units for producing the first and second frequency derivatives of the amplitude-frequency response of the oscillatory circuit, to the electronic swith, to the first and second memory units, and to the drive input of the frequency modulator.
  • the proposed apparatus offers higher accuracy of measuring the Q-quality, since the measuring error is now determined only by the error of measuring frequencies.
  • the apparatus ensures that both branches of the amplitude-frequency response curve are investigated at the same time, thus eliminating errors of measuring small Q-values due to the asymmetry of the amplitude-frequency response of the oscillatory circuit. Since the measuring error due to the frequency dependence of the transfer ratios of the measuring unit coupling elements is entirely eliminated in the proposed apparatus, the accuracy of measuring the Q-quality, especially in a high frequency range, is increased by 20% as compared with the existing instruments.
  • FIG. 1 is a block diagram of the proposed apparatus for measuring the Q-quality of oscillating circuit components, according to the present invention
  • FIG. 2 (a, b, c) illustrates signals at the outputs of the units of the apparatus in the mode of tuning to the resonance frequency, according to the present invention
  • FIG. 3 (a, b, c) illustrates signals at the outputs of the units of the apparatus in the mode of selecting the frequency passband, according to the present invention.
  • the apparatus also includes a unit 7 for producing the first frequency derivative of the amplitude-frequency response of the oscillatory circuit, said unit having its output connected to the null device 2 and its input connected to the input of a unit 8 for producing the second frequency derivative of the amplitude-frequency response of the oscillatory circuit and to the input of a peak detector 9, which input is also connected to the measuring unit 6.
  • a second input 10 of the frequency modulator 5 is electrically coupled via an electronic switch 11 to a low-frequency generator 12.
  • the apparatus includes a second control unit 13 having a null device 14 and a sawtooth generator 15 connected in series.
  • a memory unit 16 connected to the sawtooth generator 15 and to the low-frequency generator 12.
  • the memory unit 16 uses a well known circuit configuration.
  • the apparatus includes a unit 17 for measuring the frequency ratio, having likewise a well known circuit configuration and connected to the low-frequency and high-frequency generators 12 and 4, respectively. Furthermore, the apparatus includes a memory unit 18 similar to the unit 16 and electrically coupling the high-frequency generator 4 to the control unit 1.
  • the apparatus also includes a third control unit 19 having a series circuit of a multivibrator and a frequency divider, the outputs of the unit 19 being connected to the inputs of the units 7 and 8 for producing, respectively, the first and second frequency derivatives of the amplitude-frequency response of the oscillatory circuit, to the input of the electronic switch 11, to the inputs of the first and second memory units 16 and 18, respectively, and to the drive input 20 of the frequency modulator 5.
  • the apparatus includes a phase inverter 21 electrically coupling the low-frequency generator 12 to the frequency modulator 5 and having its drive input connected to the third control unit 19.
  • the latter When measuring the Q-quality of an inductor 22, the latter is connected directly to the measuring unit 6.
  • the measuring unit 6 When measuring the Q-quality of a capacitor 23, the latter is connected to the measuring unit 6 together with a matched inductor placed instead of the inductor 22.
  • plots in FIG. 2 represent the operation of the apparatus in the mode of tuning the high-frequency generator 4 to the resonance frequency of the oscillatory circuit, wherein FIG. 2a depicts voltage U 1 at the output of the peak detector 9, FIG. 2b depicts voltage U 2 at the output of the unit 7 of producing the first derivative, and FIG. 2c depicts voltage U 3 at the output of the memory unit 18.
  • Plots in FIG. 3 represent the operation of the apparatus in the mode of selecting the frequency passband between inflection points of the amplitude-frequency response curve of the oscillatory circuit, wherein FIG. 3a depicts voltage U 4 at the output of the peak detector 9, FIG. 3b depicts voltage U 5 at the output of the unit 8 of producing the second derivative, FIG. 3c depicts voltage U 6 at the output of the memory unit 16.
  • the proposed apparatus operates as follows.
  • the control unit 19 (FIG. 1) opens the memory unit 18 for a predetermined time, closes the memory unit 16 and electronic switches 11, and puts the frequency modulator 5 into the mode of selecting for high-frequency.
  • the sawtooth generator 3 produces voltage U 3 (FIG. 2c) varying linearly with time. This voltage causes to a variation in the frequency of the output voltage of the high-frequency generator 4, this output voltage being delivered via the frequency modulator 5 to the input of the measuring unit 6.
  • the components to be measured i.e., the inductor 22 and capacitor 23, are connected to the measuring unit 6, the latter becomes an oscillatory circuit.
  • the unit 7 driven by the unit 19 differentiates the voltage U 1 so that voltage U 2 (FIG. 2b) is developed at its output, the voltage U 2 being proportional to the first frequency derivative of the amplitude-frequency response of the circuit.
  • the voltage U 2 drives the null device 2 (FIG. 1) which, in turn, drives the sawtooth generator 3 so that upon passage of the voltage U 2 (FIG. 2b) through zero, the null device establishes constant voltage U 3 (FIG. 2c) at the output of the generator 3, said constant voltage holding a frequency of the output voltage of the high-frequency generator 4 (FIG. 1) which is equal to the natural resonance frequency of the oscillatory circuit.
  • the control unit 19 closes the memory unit 18 for a predetermined time, opens the unit 16 and electronic switch 11, and puts the frequency modulator 5 into the mode of selecting the side (sum of difference) frequency.
  • the memory unit 18 stores voltage U 3 (FIG. 3c) and, therefore, a frequency of the output voltage of the high-frequency generator 4 (FIG. 1) which is equal to the natural resonance frequency of the oscillatory circuit.
  • the sawtooth generator 15 produces voltage U 6 (FIG. 3c) linearly varying with time.
  • This voltage U 6 causes a change in the frequency of the output voltage of the low-frequency generator 12 (FIG. 1), said output voltage being delivered via the phase inverter 21 and electronic switch 11 to the input of the frequency modulator 5.
  • f o is the frequency of the high-frequency generator
  • F is the frequency of the low-frequency generator.
  • the voltage of high varying frequency is converted into voltage U 4 (FIG. 3a) varying with time and corresponding to the amplitude-frequency response of the oscillatory circuit under measurement.
  • the unit 8 (FIG. 1) driven by the unit 19 differentiates voltage U 4 (FIG. 3a) so that voltage U 5 (FIG. 3b) is developed at its output, the voltage U 5 being proportional to the second frequency derivative of the amplitude-frequency response of the oscillatory circuit.
  • the voltage U 5 drives the null device 14 (FIG. 1) which, in turn, drives the sawtooth generator 15 and establishes constant voltage U 6 (FIG. 3c) at the output thereof upon passage of voltage U 5 through zero, the voltage U 6 holding the output voltage frequency of the low-frequency generator 12 (FIG. 1) which is half as much as the frequency passband of the oscillatory circuit between the inflection points of its amplitude-frequency response curve.
  • the phase inverter 21 driven by the unit 19 provides simultaneous sampling for both branches of the amplitude-frequency response so that when measuring small Q-values, it is an average value of the half passband for the left and right branches of the amplitude-frequency response curve that is determined.
  • the "Q" is directly measured by the unit 17 for measuring the frequency ratio.
  • the unit 17 also measures a given operating frequency at which Q-measurements are being performed, the operating frequency being set by a variable capacitor of the measuring unit.
  • the apparatus proposed herein features higher accuracy of Q-quality measurements, as compared to the prior art measuring devices.

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  • Engineering & Computer Science (AREA)
  • Power Engineering (AREA)
  • Physics & Mathematics (AREA)
  • General Physics & Mathematics (AREA)
  • Measurement Of Resistance Or Impedance (AREA)
  • Measuring Frequencies, Analyzing Spectra (AREA)
US05/837,849 1976-10-01 1977-09-29 Apparatus for measuring q-quality of oscillatory circuit components Expired - Lifetime US4136313A (en)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
SU762408263A SU750389A1 (ru) 1976-10-01 1976-10-01 Устройство дл измерени добротности колебательных контуров
SU2408263 1976-10-01

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US4136313A true US4136313A (en) 1979-01-23

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US (1) US4136313A (de)
JP (1) JPS5388769A (de)
CS (1) CS196800B1 (de)
DE (1) DE2744122C3 (de)
FR (1) FR2366575A1 (de)
GB (1) GB1550062A (de)
SU (1) SU750389A1 (de)

Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US20050265428A1 (en) * 2000-05-26 2005-12-01 Freescale Semiconductor, Inc. Low power, high resolution timing generator for ultra-wide bandwidth communication systems
US6975665B1 (en) * 2000-05-26 2005-12-13 Freescale Semiconductor, Inc. Low power, high resolution timing generator for ultra-wide bandwidth communication systems
US20110122921A1 (en) * 2000-10-10 2011-05-26 Freescale Semiconductor, Inc. Low power, high resolution timing generator for ultra-wide bandwidth communication systems

Families Citing this family (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE68901462D1 (de) * 1988-01-22 1992-06-17 Atomic Energy Authority Uk Material-charakterisierung.

Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3824458A (en) * 1973-01-22 1974-07-16 A Martyashin Device for measuring parameters of elements of parallel lc-circuit
US3843925A (en) * 1973-06-11 1974-10-22 V Shlyandin Method for measuring parameters of complex electric circuit components and device for effecting same
US3846699A (en) * 1973-07-16 1974-11-05 A Morozov Method and device for measuring parameters of resonant lc circuit elements
US3848186A (en) * 1973-08-24 1974-11-12 A Martyashin Method of measuring parameters of complex electric circuit and device for effecting same

Family Cites Families (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2671198A (en) * 1951-04-12 1954-03-02 Sperry Corp Method and apparatus for measuring the frequency response of translating devices
US2692947A (en) * 1951-05-11 1954-10-26 Sperry Corp Locator of inflection points of a response curve

Patent Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3824458A (en) * 1973-01-22 1974-07-16 A Martyashin Device for measuring parameters of elements of parallel lc-circuit
US3843925A (en) * 1973-06-11 1974-10-22 V Shlyandin Method for measuring parameters of complex electric circuit components and device for effecting same
US3846699A (en) * 1973-07-16 1974-11-05 A Morozov Method and device for measuring parameters of resonant lc circuit elements
US3848186A (en) * 1973-08-24 1974-11-12 A Martyashin Method of measuring parameters of complex electric circuit and device for effecting same

Cited By (8)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US20050265428A1 (en) * 2000-05-26 2005-12-01 Freescale Semiconductor, Inc. Low power, high resolution timing generator for ultra-wide bandwidth communication systems
US6975665B1 (en) * 2000-05-26 2005-12-13 Freescale Semiconductor, Inc. Low power, high resolution timing generator for ultra-wide bandwidth communication systems
US7643533B2 (en) 2000-05-26 2010-01-05 Freescale Semiconductor, Inc. Agile clock mechanism and method for ultrawide bandwidth communications system
US20100135358A1 (en) * 2000-05-26 2010-06-03 Freescale Semiconductor Inc. Low power, high resolution timing generator for ultra-wide bandwidth communication systems
US7903778B2 (en) 2000-05-26 2011-03-08 Freescale Semiconductor, Inc. Low power, high resolution timing generator for ultra-wide bandwidth communication systems
US20110122921A1 (en) * 2000-10-10 2011-05-26 Freescale Semiconductor, Inc. Low power, high resolution timing generator for ultra-wide bandwidth communication systems
US8311074B2 (en) 2000-10-10 2012-11-13 Freescale Semiconductor, Inc. Low power, high resolution timing generator for ultra-wide bandwidth communication systems
US8743927B2 (en) 2000-10-10 2014-06-03 Freescale Semiconductor, Inc. Low power, high resolution timing generator for ultra-wide bandwidth communication systems

Also Published As

Publication number Publication date
DE2744122A1 (de) 1978-04-06
GB1550062A (en) 1979-08-08
SU750389A1 (ru) 1980-07-23
JPS5388769A (en) 1978-08-04
DE2744122C3 (de) 1980-09-04
DE2744122B2 (de) 1980-01-10
FR2366575B1 (de) 1981-01-16
CS196800B1 (en) 1980-04-30
FR2366575A1 (fr) 1978-04-28

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